Re: [PATCH V4 11/27] ublk: handle UBLK_U_IO_COMMIT_IO_CMDS

Ming Lei
2025-12-01T10:26:23Z

On Sun, Nov 30, 2025 at 08:39:49AM -0800, Caleb Sander Mateos wrote:
> On Thu, Nov 20, 2025 at 5:59 PM Ming Lei <ming.lei@redhat.com> wrote:
> >
> > Handle UBLK_U_IO_COMMIT_IO_CMDS by walking the uring_cmd fixed buffer:
> >
> > - read each element into one temp buffer in batch style
> >
> > - parse and apply each element for committing io result
> >
> > Signed-off-by: Ming Lei <ming.lei@redhat.com>
> > ---
> > drivers/block/ublk_drv.c | 117 ++++++++++++++++++++++++++++++++--
> > include/uapi/linux/ublk_cmd.h | 8 +++
> > 2 files changed, 121 insertions(+), 4 deletions(-)
> >
> > diff --git a/drivers/block/ublk_drv.c b/drivers/block/ublk_drv.c
> > index 66c77daae955..ea992366af5b 100644
> > --- a/drivers/block/ublk_drv.c
> > +++ b/drivers/block/ublk_drv.c
> > @@ -2098,9 +2098,9 @@ static inline int ublk_set_auto_buf_reg(struct ublk_io *io, struct io_uring_cmd
> > return 0;
> > }
> >
> > -static int ublk_handle_auto_buf_reg(struct ublk_io *io,
> > - struct io_uring_cmd *cmd,
> > - u16 *buf_idx)
> > +static void __ublk_handle_auto_buf_reg(struct ublk_io *io,
> > + struct io_uring_cmd *cmd,
> > + u16 *buf_idx)
>
> The name could be a bit more descriptive. How about "ublk_clear_auto_buf_reg()"?

Looks fine.

>
> > {
> > if (io->flags & UBLK_IO_FLAG_AUTO_BUF_REG) {
> > io->flags &= ~UBLK_IO_FLAG_AUTO_BUF_REG;
> > @@ -2118,7 +2118,13 @@ static int ublk_handle_auto_buf_reg(struct ublk_io *io,
> > if (io->buf_ctx_handle == io_uring_cmd_ctx_handle(cmd))
> > *buf_idx = io->buf.auto_reg.index;
> > }
> > +}
> >
> > +static int ublk_handle_auto_buf_reg(struct ublk_io *io,
> > + struct io_uring_cmd *cmd,
> > + u16 *buf_idx)
> > +{
> > + __ublk_handle_auto_buf_reg(io, cmd, buf_idx);
> > return ublk_set_auto_buf_reg(io, cmd);
> > }
> >
> > @@ -2553,6 +2559,17 @@ static inline __u64 ublk_batch_buf_addr(const struct ublk_batch_io *uc,
> > return 0;
> > }
> >
> > +static inline __u64 ublk_batch_zone_lba(const struct ublk_batch_io *uc,
> > + const struct ublk_elem_header *elem)
> > +{
> > + const void *buf = (const void *)elem;
>
> Unnecessary cast

OK

>
> > +
> > + if (uc->flags & UBLK_BATCH_F_HAS_ZONE_LBA)
> > + return *(__u64 *)(buf + sizeof(*elem) +
> > + 8 * !!(uc->flags & UBLK_BATCH_F_HAS_BUF_ADDR));
>
> Cast to a const pointer?

OK, but I feel it isn't necessary.

>
>
> > + return -1;
> > +}
> > +
> > static struct ublk_auto_buf_reg
> > ublk_batch_auto_buf_reg(const struct ublk_batch_io *uc,
> > const struct ublk_elem_header *elem)
> > @@ -2708,6 +2725,98 @@ static int ublk_handle_batch_prep_cmd(const struct ublk_batch_io_data *data)
> > return ret;
> > }
> >
> > +static int ublk_batch_commit_io_check(const struct ublk_queue *ubq,
> > + struct ublk_io *io,
> > + union ublk_io_buf *buf)
> > +{
> > + struct request *req = io->req;
> > +
> > + if (!req)
> > + return -EINVAL;
>
> This check seems redundant with the UBLK_IO_FLAG_OWNED_BY_SRV check?

I'd keep the check, which has document benefit, or warn_on()?

>
> > +
> > + if (io->flags & UBLK_IO_FLAG_ACTIVE)
> > + return -EBUSY;
>
> Aren't UBLK_IO_FLAG_ACTIVE and UBLK_IO_FLAG_OWNED_BY_SRV mutually
> exclusive? Then this check is also redundant with the
> UBLK_IO_FLAG_OWNED_BY_SRV check.

OK.

>
> > +
> > + if (!(io->flags & UBLK_IO_FLAG_OWNED_BY_SRV))
> > + return -EINVAL;
> > +
> > + if (ublk_need_map_io(ubq)) {
> > + /*
> > + * COMMIT_AND_FETCH_REQ has to provide IO buffer if
> > + * NEED GET DATA is not enabled or it is Read IO.
> > + */
> > + if (!buf->addr && (!ublk_need_get_data(ubq) ||
> > + req_op(req) == REQ_OP_READ))
> > + return -EINVAL;
> > + }
> > + return 0;
> > +}
> > +
> > +static int ublk_batch_commit_io(struct ublk_queue *ubq,
> > + const struct ublk_batch_io_data *data,
> > + const struct ublk_elem_header *elem)
> > +{
> > + struct ublk_io *io = &ubq->ios[elem->tag];
> > + const struct ublk_batch_io *uc = &data->header;
> > + u16 buf_idx = UBLK_INVALID_BUF_IDX;
> > + union ublk_io_buf buf = { 0 };
> > + struct request *req = NULL;
> > + bool auto_reg = false;
> > + bool compl = false;
> > + int ret;
> > +
> > + if (ublk_dev_support_auto_buf_reg(data->ub)) {
> > + buf.auto_reg = ublk_batch_auto_buf_reg(uc, elem);
> > + auto_reg = true;
> > + } else if (ublk_dev_need_map_io(data->ub))
> > + buf.addr = ublk_batch_buf_addr(uc, elem);
> > +
> > + ublk_io_lock(io);
> > + ret = ublk_batch_commit_io_check(ubq, io, &buf);
> > + if (!ret) {
> > + io->res = elem->result;
> > + io->buf = buf;
> > + req = ublk_fill_io_cmd(io, data->cmd);
> > +
> > + if (auto_reg)
> > + __ublk_handle_auto_buf_reg(io, data->cmd, &buf_idx);
> > + compl = ublk_need_complete_req(data->ub, io);
> > + }
> > + ublk_io_unlock(io);
> > +
> > + if (unlikely(ret)) {
> > + pr_warn("%s: dev %u queue %u io %u: commit failure %d\n",
> > + __func__, data->ub->dev_info.dev_id, ubq->q_id,
> > + elem->tag, ret);
>
> This warning can be triggered by userspace. It should probably be
> rate-limited or changed to pr_devel().

Looks fine.

Thanks,
Ming